Abiotic stress has a major impact on plant growth and performance, crop yields being significantly decreased as a result of the cessation of growth under conditions of mild stress. Growth arrest arises from a cessation of cell division in meristems. The cell cycle stops in G1 phase in response to changes in the glutathione [GSH] pool, which is itself a measure of abiotic stress. Poly(ADP)ribose polymerase (PARP) provides a further link between abiotic stress and the cell cycle, as down-regulation of this enzyme enhances plant stress tolerance. The present project links cell cycle regulation and stress biology, building on existing expertise in redox metabolism and growth regulation at the host laboratory. This project will exploit the essential know-how in cellular redox metabolism, cell cycle regulation, proteomics and microarrays to elucidate and characterise the components that regulate the recruitment of GSH into the nucleus and influence cell cycle progression and abiotic stress tolerance, through the regulation of nuclear proteins such as PARP. The overall aim is to understand the redox regulation of nuclear proteins by GSH and specifically how the nuclear and cytoplasmic GSH pools modify nuclear gene expression and nuclear protein function/activity during the cell cycle.